Thursday, October 14, 2010

A standard for GraphDB

Yesterday GraphDBs have covered a niche market. In the last period things are changed and they are becoming much more popular than ever. This is due to:

The always growing need to have data strongly interconnected. What better than a GraphDB for it?

Applications are much more "social" than before. And social means relationships among subjects that perfectly bound to the Graph model

Performance on large datasets. You can live without a pure GraphDB, and therefore continue to use a Relational DBMS, until you need a real fast access to your data

The NoSQL movement has contributed a lot to change the mind of developers to focus to DBMS different (and sometime very different) from the Relational model.

The GraphDB has few but strong concepts. Graphs are composed by:

Vertex or Node, the linked entity. Vertexes can have properties.

Edge or Arc, as the link between the Vertexes. Edges can have properties and can be unidirectional or bidirectional

Property, is a value to assign to Vertexes and Edges. A property has a name and a value

Each GraphDB product is based upon the above concepts, but features can be very different among them. Furthermore there isn't a standard for them and an application can't migrate from one to another one at zero or low cost.

This is the reason why I want to introduce the Tinkerpop Blueprints. This Open Source project aims to have a shared set of basic interfaces to abstract the concepts of Graph, Vertex, Edge and Property. In this way applications can easily migrate to another available implementation of the specification.

Furthermore Tinkerpophas created a complete stack of tools and framework to work with Graphs. Below the main ones:

Gremlinis a Turing-complete, graph-based programming language designed for key/value-pair multi-relational graphs. Gremlin makes use of an XPath-like syntax to support complex graph traversals. This language has application in the areas of graph query, analysis, and manipulation.

Rexsteris a RESTful graph shell that exposes any Blueprints graph as a standalone server. Extensions support standard traversal goals such as search, score, rank, and, in concert, recommendation. Rexster makes extensive use of Blueprints, Pipes, and Gremlin. In this way its possible to run Rexster over various graph systems.

Pipesis a graph-based data flow framework for Java 1.6+. A process graph is composed of a set of process vertices connected to one another by a set of communication edges. Pipes supports the splitting, merging, and transformation of data from input to output.

While the .NET porting is interesting I'd like to provide a .NET driver for OrientDB as first thing. The best would be to implement the binary protocol to achieve the best performance, but the HTTP/RESTful one is easier to implement.